ISO is an acronym for the International Organization for Standardization, which sets standards for various industries, including photography.

ISO controls the sensitivity of the camera's sensor to light, allowing photographers to adjust the brightness of their images.

ISO primarily affects the brightness of an image by adjusting the sensitivity of the sensor to light.

Increasing the ISO value typically results in more noise or grain in the image due to the amplification of the signal from the sensor.

A low ISO setting is suitable for bright outdoor conditions where there is ample light, as it minimizes noise and preserves image quality.

A high ISO setting is useful in low-light conditions to increase the sensor's sensitivity to light, allowing you to capture images without excessive underexposure.

ISO does not directly affect the depth of field. Depth of field is controlled by the aperture setting and the focal length of the lens.

For general photography, an ISO range of ISO 200-800 is typically recommended to balance image quality and noise levels.

Increasing the ISO value allows you to use a faster shutter speed to freeze motion or capture images in low-light conditions without camera shake.

ISO and aperture have an inverse relationship. Increasing the ISO value allows you to use a smaller aperture (higher f-number) to achieve the same exposure, and vice versa.

ISO 640 is not a standard ISO value commonly used in photography. Typical ISO values include ISO 100, 200, 400, 800, 1600, 3200, and higher.

In astrophotography, a low ISO setting is used to minimize noise and preserve image quality, especially when capturing long exposures of the night sky.

ISO does not directly affect the dynamic range of an image. Dynamic range is primarily determined by the camera's sensor and its ability to capture a wide range of tones from bright highlights to dark shadows.

Camera sensor size does not directly influence the choice of ISO. ISO is primarily determined by the available light, desired shutter speed, and depth of field requirements.

For capturing fast-moving subjects, a higher ISO setting in the range of ISO 1600-3200 is often used to freeze motion and avoid blurry images.